Desalination Overview

Desalination describes a range of processes that remove salts and other minerals, as well as most biological and organic compounds, from saline water to produce high-quality water suitable for drinking. The earth’s natural water cycle – evaporation and rainfall, driven by solar energy – is an example of desalination in action.

The ancient Greek philosopher Aristotle pioneered the use of evaporation and distillation to turn seawater into potable water. For decades, countries in arid, energy-rich regions like the Persian Gulf have used energy-intensive thermal distillation of seawater to meet fresh water needs. Only with the advent of reverse osmosis technology in the late 20th century, though, has desalination become an economic option for large-scale public water supplies in other parts of the world.

​Sea Water Reverse Osmosis or “SWRO” has emerged as the most common water desalination technology used in the United States. Rather than thermal distillation, SWRO technology uses a much more energy-efficient process. Hydraulic pressure is used to force seawater or brackish water, at ambient temperature, through a semi-permeable membrane. This process separates pure water molecules from salt ions and other large molecules, including virtually all viruses and bacteria.​The reverse osmosis spiral module at the heart of SWRO technology was patented in 1964 by General Atomics of San Diego, California. After decades of cost reduction and efficiency improvements, reverse osmosis technology now offers a proven, cost-effective solution for areas prone to water shortages. As of 2015, over 15,000 desalination plants were in service in 120 countries worldwide, yielding over 20 billion gallons per day of potable water from seawater and brackish sources; more than 80% of this production uses the RO process. Israel now sources more than half of its national drinking water supply from the Mediterranean Sea using SWRO technology similar to the type that Poseidon has now brought to North America.